Boring bar



Sept-22, 1931- F. s. HARTWYEILL BORING BAR Filed'Dec. 2a, 1926 2 Sheets-Sheet P 22, 1931- F. s. HARTWELL 1,824,543

BORING BAR- Filed Dec. 28 1925 2 Sheets-Sheet 2 Patented Sept. 22, 1931 PATE T euce) J mm m 1 .A ppI ioatibn mm Uecemlien 23, 192$ 'sariar m... 157,572:

inventibn relates: toexpansion Bering,

totals and particularlyto such as are known as boring' bars-L The matter of providing an adequate eut- 5. ter' adjhst-ing means for expansion boring bars,',wi'th0ut' necessitating a housing slot or recess of such-size-as' to materially weaken tliebar at the site Of the Cutters; has always been a stumb'linghleek for teolfmakers, and

I particularly so-,i-'n the smaller sizes; of bars Boring bars are subj'ected t0 heavytersional strain at the cutter-sites, and when the baris equipped" with initially acting roughing cut ters followed. byfinishing cutters; it will beevident" that the heavy uneven ent" of the roughing cutters creates a very substantial torque l'oad that haste-he met by t he'weakened cross sectien 02% the bar which carries the fin ishing cutters-1 Attempts to' overeeme: the cross; sectional weakness o-f the bar at the: cut-- ters byma-teriall-y reducing the size of the bar slht' and eutteradfiusting means have met with manuiaeturing and other drawbacks; Specifically, the proposed adjusting means:

have involved an. unnecessary number of:

working parts which are dilficultto; producesmall" sizes; hard to asseinble and more: or." less unreliable i-n practieal'usea It is; therefore, the primary object: of: my?

invention to overcome the: aforenotecl 0hjections and to provide a; boring inwhielr the arrangement Qt the-blades; and the-heldingand adjusting meanszt-hereton isasueha that a substantial reduction in the size ofttlieeopena or openings for the reeeptinn; 0t these parts is made possible whereby the strength ef the bar adjaeent theieutting units-will: come pare favorably with the strength ezfi'thei bar elsewhere also to'turnish agreatlysimplifiedr 2 eutteradj usti-ng'and holding meanswhichiine cerperatesaminimuln number of parts whieh may bemanutfiactured lI'li small sizes without loss of eflicieney; thereby adaptingrtheideviee. for the smallest sizes 1 0i boring bars without 1 materially weakening the same.

Atnether object ofithe inventionqistheprorvisie'lr in a: boring bar of: anradju'stingi and holding means for the cutters which" is: s6 termed and arranged that it m'ay be posi tioned directly in theeutter carrying slots 1 of the bar, andl when so p'ositianed f-imet iens to; direetly'support the cutters. The foregoing; and other oltiects', to be ferred te-late-r, are attained by means of a novel combination and arrangement ofparts to be hereinafter diascri'hed andi claimed and order that the same may be betfter under": stoo'd, referene'esfis had tethe-aeeempanying drawings ferming a part 0t this speeiliew tron. The drawings illustrate what I new regard as a preferred enrhedi'rnentief the in mention, but it is'te be understand} that V22 ri'euschanges and medi fieatibns may he-made" therein without departingfrem': the spirit and scope oi the subject matter claimed.

' the drawings; whereinthe same refer-'- ence charactersdesignate: the sameparts in" all views,

- Figure I is an elevatielr ef a boring harim V t e line-- s -e 0s in Figure 2;- the slot 7 is: somewhat wider than the cutters 83 to aeeommedate' the cutter adjusting bl'ecks 9 and their leaking bar IO;-

these elements; having a snug sliding fit in the: slot g The-drawingsillustrate-a barhaving a' pair at finishing cutters 8 and an adjusting and holding block 9 for each Howeverit is" 130 be=-'understood, 0t course, that the ihven-- tion: is capable of expression: in a barhavihg: but one-cutter,- the specific: number ot'cutters; or sets of cutters being; immaterial;

Referring to Figures 2 and: 5 it is ohserved that the: adjusting and holding blacks 9? are of rectangular form, each; being provided with a; projecting"'lu'g 9w snugly engaging im the recesses 13 is such that the plates 12 serve the additional function of closing the slots 7 adjacent the cutters 8, the ends of the plates12 bearing against the adjacent edges of the cutters to maintain the opposite edges 7 thereofin sliding engagement with the proximate slot wall; However, it is pointed out that the adjusting blocks 9 and their associated locking bar constitute the major supporting instrumentality for the cutters 8;

This is evident from an inspection of Figure 2, since'it is seen that the opposed surfaces ofthe blocks 9 are in flat contact with the locking bar 10 and the edges of the cutters 8, respectively. Furthermore, the ends of the lugs 9a flatlyengage the back walls of the cutter notches Set. I

From the construction described, it is manifest that an entirely adequate and satisfactory bearing will be provided for the blockengaged edges of the cutters 8 without subjecting the screw journal plates 12 to unusual strain.

In carrying out the invention, the ends of the adjusting screw 11 may have an an ular socket 11a for the application of an Ellen wrench when it is desired to adjust the cutters 8. However, any other equivalent formation of the screw ends may be resorted for the engagement of an operating implement.

- The locking bar 10, as hereinbefore intimated is designed to lock the cutters 8 in a predetermined adjusted position. To,this end the back surface of the bar 10whichengages the adjacent end wall of the slot 7 is cut with rounded transverse grooves 10a tapering in the direction of one end. These locking bar grooves 10a, preferably two in number, register with transverse bores 15 extending 7 through the bar 6 and opening into the cutter slot 7 thereof. The bores 15 are threaded at one end to receive the threaded outer ends of adjusting screws 16, having intermediate shank portions 16a tapering in frustro conical fashion in the direction of their reduced cylindrical ends 16?) which are received and guided in the diametrically reduced end portions 15a of the bores 15. On tightening the screws 16 their tapered portions 16a wedge into the correspondingly tapered lockingblock grooves 100. forcing the locking-block 10 against the adjusting blocks 9 and the lat.-

. ter into binding contact with the cutters 8 to tive positionthevery slight transverse play in the threads of the adjusting blocks 9 and their feed screw 11 allows the blocks to bind the cutters in place in addition to so binding the blocks on the feed screw as to prevent turning of the latter.

Assembly of the cutter adjusting parts in the bar slot 7 is simple. The cutters 8 are first introduced into the slot followed by the adjusting blocks 9,.duly mounted on their feed screw 11. When applying the adjusting blocks 9v to the oppositely threaded ends of feed screw '11, care must be taken to see that both blocks take. in the screw threads at the same time, as otherwise the blocks will not occupy the same relative position and one cutter will be projected a greater distance from the bar than the other. The adjusting bloc-k lugs 9a, having been engaged with their respective cutter notches 8a, the locking bar10 is put in place and its adjusting and holding screws 16 inserted in the boring bar holes 15 to engage the tapered edge recesses 10a of the locking bar. Plates 12 are now applied.

It will be seen that the holding and adjusting elements are'of the same thickness as the cutters and that these parts are arranged directly behind the cutters in normal supporting or hearing contact therewith and with the opposite wall of the cutter slot. By this structure a single slot of minimum width serves to accommodate the cutters and their supporting and adjusting elements. Thus, the strength of the boring bar at the site of the cutters compares favorably "with the strength of the bar elsewhere. Furthermore the carrying plates 12 of the block adjusting screw 11 are relieved of practically all strain when, the tool is in use.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. A boring bar having a slot and a pair of cutters therein, an adjusting block for each of said cutters and carried in said slot, the blocks operatively engaging and flatly contacting against one edge of their respective cutters, a backing member engaging one wall of said slot'and having a plane, unobstructed opposite side surface acting through flat contact with said adjusting blocks for slidably retaining said cutters against the opposite slot wall, a screw'having oppositely threaded end portions, said adjustingblocks being operatively mounted upon the respective ends of said screw, removable plates carried at opposite sides of said bar and in which the ends of said screw are journallegl,

said plates engaging opposite ends of said backing member to center the same and hold it against shifting endwise in said slot, the

ends of plates bearing against the cutters and comprising, an auxiliary sustaining means therefor, said plates being arranged to close the said slot adjacent said cutters whereby to removably confine said screw, ad-

justing blocks and backing member in said slot, said plates having openings whereby access may be had to said screw for turning the same to adjust, said cutters, and wedge screws carried by said bar, said wedge screws being disposed transversely of and acting through said backing member and adjusting blocks for holding the cutters in a set I position, and the rear edge of said backing locking said cutter in a set position, auxiliary bar-carried sustaining means for said cutter and acting independently of saidlast named means for holding said backing member in said slot, said boring bar and backing member having recesses for receiving said locking means, and said auxiliary bar car ried sustaining means engaging said removable backing member to hold said recesses in alignment.

3. A boring bar having a shoulder and an adjustable cutter bearing against said shoulder, a sustaining and adjusting block operatively engaging said cutter,a backing and sustaining member for said adjusting block and removably carried by said bar to permit disengagement of said adjusting block from said cutter, said backing and sustaining member acting through said adjusting block for sustaining said cutter against said shoulder, means for actuating said backing member to lock said cutter in a set position, auxiliary bar-carried cutter sustaining means removably carried by said bar and positioned to prevent removal of said backing member, said last-named means being independent of said backing member-actuating means, said boring bar and backing member having means cooperating to provide a seat for said actuating means, and sa1d auxiliary cutter sustaining means engaging opposite ends of said backing member to hold the seating portions of the bar and backing member in registry.

In testimony whereof I aflix my signature.

FLOYD S. HARTWELL. 

